Star formation in the nearby Andromeda Galaxy (M31) has been slowing down over the last 500 million years, according to a new study using Hubble Space Telescope data.  The study was published July 27, 2026, in The Astrophysical Journal. Lead author Tobin Wainer, an astronomer at the University of Washington, and his team used dataContinue reading "Andromeda’s star formation is slowing down"

The post Andromeda’s star formation is slowing down appeared first on Astronomy Magazine.

Les trous noirs supermassifs qui font évoluer les galaxies nous réservent sans aucun doute des surprises. La dernière en date concerne maintenant les amas de galaxies et leurs interactions avec ces astres compacts géants.

NASA’s Neil Gehrels Swift Observatory captured an “orphan” black hole lighting up as it devoured a star on the outskirts of a faraway galaxy. These phenomena are rare to begin with, and none had ever before been seen so far outside of a galaxy’s core.

“We were looking for these star-shredding events as a way to find otherwise invisible supermassive black holes wandering away from the galactic cores where they usually reside,” said Robert Stein, a research fellow at The University of Maryland, College Park and NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “With this discovery, which is one of just a couple that have been confirmed so far, we’ve validated a new technique and can use it to hunt for more.”

A paper describing the results, led by Stein, was published Monday in The Astrophysical Journal Letters.

Researchers saw an ultrabright flare unleashed by a star being torn apart by extreme gravitational forces after drifting too close to a monster black hole — a phenomenon called a tidal disruption event. The black hole behind the blast weighs in at about a million times the Sun’s mass. Its existence was first flagged in November 2025 as an unusual brightening in a galaxy about 750 million light-years away by ZTF (Zwicky Transient Facility), a survey conducted by the Palomar Observatory in Southern California.

“Out of the half million flashes ZTF detects each night, our new artificial intelligence algorithm automatically recognized a flare that looked a lot like a tidal disruption event, despite its unusual location in the outskirts of a galaxy,” Stein said. For a few months, the tidal disruption event outshone its entire host galaxy in ultraviolet wavelengths, temporarily radiating with the light of about 10 billion suns.

Other telescopes, including the SOAR (Southern Astrophysical Research) telescope in Chile, followed up on the ZTF source to look at the event’s spectrum, which revealed features supporting that it was likely a tidal disruption event. Astronomers then used NASA’s Swift to look at wavelengths they can’t detect with ground-based telescopes to uncover new information. For example, Swift’s UVOT (Ultraviolet/Optical Telescope) took the blip’s temperature and found that it had quite a fever at about 54,000 degrees Fahrenheit (30,000 degrees Celsius).

“The combination of all this data helped us rule out other explanations and confidently say it’s a tidal disruption event, despite its strange location,” said Jonathan Carney, a doctoral student at the University of North Carolina at Chapel Hill, who took the first spectra that supported the flare’s interpretation as a tidal disruption event.

Hidden heavyweights

Nearly every galaxy in the universe is anchored by a supermassive black hole sitting right in the center. About once every 100,000 years, a star will drift too close to this invisible heavyweight and trigger a tidal disruption event.

While they’re rather rare in any given galaxy, scientists scour millions of galaxies for them. Each year, astronomical surveys typically spot about 30 tidal disruption events occurring somewhere in the universe.

Prior to 2024, they’d only been seen in galaxy cores. That’s partly because astronomers mainly looked for them there; after all, it’s where all the known supermassive black holes were, and you can’t get a tidal disruption event without one (the gravitational pull of lighter black holes isn’t strong enough).

Then scientists saw the telltale signs of a star being shredded 2,600 light-years from the center of its host galaxy. That inspired more astronomers to look beyond galaxy cores for similar events, and now a team has identified one more than 30,000 light-years away from a galaxy’s center.

Oddball origin story

So how did the newfound black hole become so off-kilter?

“It must have originated in a galaxy’s center, but not the one it’s in the outskirts of now,” Stein said. “We think the host galaxy’s supermassive black hole is still at its core, but the one eating the star could have started off in a small galaxy that merged with the big one we see today.”

The researchers have outlined two possibilities. Three or more galaxies may have merged together, and the gravitational tug-of-war between their central supermassive black holes may have flung the lightest black hole out to the galaxy’s edge.

Or a dwarf galaxy could be midway through a merger. As the dwarf’s stars fell into the larger galaxy, one may have passed too close to the dwarf’s supermassive black hole.

“Further discoveries could reveal the origin of this apparent ‘orphan’ black hole,” Stein said. “The key science question we want to answer is: How common are wandering black holes?”

The answer may soon be within reach. “Pointed science observations with Swift’s UVOT and XRT (X-Ray Telescope) instruments are temporarily suspended as the mission awaits an orbit boost, which is planned for this summer,” said co-author S. Bradley Cenko, Swift’s principal investigator at NASA Goddard. The spacecraft, whose primary mission ran from 2004 to 2006, is slowly sinking toward Earth due to atmospheric drag after more than 20 years of observations of the changing universe. Nudging it to a higher orbit could extend its lifetime even longer. “Once it resumes normal operations, Swift could continue searching for more examples of out-of-place black holes.”

In the coming years, scientists will use the new technique to search for disintegrating stars in observations from the newly operational Vera C. Rubin Observatory, jointly funded by the U.S. Department of Energy and National Science Foundation, in Chile and NASA’s upcoming Nancy Grace Roman Space Telescope.

“Rubin’s wide, deep surveys will reveal a much larger sample of tidal disruption events than current observatories are capable of collecting, including ones that are off-center,” Carney said. “And Roman’s space-based surveys will extend the current search zone by seeing ones that are farther away, looking back through 9 billion years of cosmic history.” Adding their observations to Swift’s and those from ground-based observatories will bring astronomers closer than ever before to completing a census of the universe’s behemoth black holes.

To learn more about the Swift mission, visit:

https://nasa.gov/swift

By Ashley Balzer
NASA’s Goddard Space Flight Center, Greenbelt, Md.

Media contact:

Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, Md.
301-286-1940

A new study using data from NASA’s Hubble Space Telescope finds that star formation in the nearby Andromeda galaxy has undergone a 500-million-year decline, with an even steeper drop in the last 40 million years. Andromeda, a spiral galaxy comparable in size to our Milky Way, is close enough to be seen with the unaided eye from areas with dark skies. Located about 2.5 million light-years from Earth, practically our cosmic backyard, Andromeda offers an opportunity for astronomers to examine its stellar populations in detail, leading to better understanding of the past of galaxies like our own.

The results published Monday in The Astrophysical Journal.

To reach this conclusion, the researchers combined data from two Hubble surveys: the Panchromatic Hubble Andromeda Treasury and the Panchromatic Hubble Andromeda Southern Treasury. Together, these two surveys mapped two-thirds of the disk of Andromeda in ultra-sharp detail. In total, the team measured about 200 million individual stars across the galaxy, giving them a detailed picture of Andromeda’s past activity.

“We need to measure the individual stars because they are the fossil record of the galaxy’s formation. Hubble is the only telescope that can give you high enough spatial resolution over a large enough area to be able to do that in Andromeda,” said Ben Williams, astronomer at the University of Washington and a co-author on the study.

Massive stars are bluer and short-lived, while less massive stars are redder and longer-lived. As a result, areas that have experienced recent star formation tend to have a larger fraction of blue stars, while areas with less recent star formation typically have a redder population. The team divided the Andromeda images into thousands of squares, spanning 300 light-years on each side of the square, and determined the history of star formation within each parcel to gain a comprehensive view of the galaxy’s past.

Steady decline

Previous research showed the Andromeda galaxy experienced a dramatic burst of star formation about 2 billion years ago, likely due to a past interaction or merger with another galaxy. Since that time, star formation has been steadily declining.

Astronomers measure the rate of star formation in terms of the mass, or amount of gas and dust, converted into stars per year. The researchers calculated that, 500 million years ago, Andromeda formed stars at a rate of about one solar mass per year. However, the formation rate dropped to about half that by 40 million years ago. The current rate has plummeted even farther, to about one-fifth the mass of our Sun per year.

The team also examined whether that decline was consistent across the galaxy or concentrated in certain areas. They found that much of the recent star formation has occurred in a star-forming ring located about 32,000 light-years from the galaxy’s center. As a result, much of the decline they measure is driven by decreasing activity within that ring.

Rather than being the result of reduced material from which new stars can form, the decline is more likely to be a natural winding down from its previous, more active state.

“It’s just like after running a marathon, sometimes you’ve got to take a bit of a breather,” said Tobin Wainer, lead author, University of Washington.

Likely suspect

The team also investigated whether there was any connection between the decrease of activity in Andromeda and its proximity to satellite galaxy M32 (Messier 32). The M32 galaxy is separated from Andromeda by about 16,000 light-years in the plane of the sky; however, its 3D location in space is uncertain. As a result, astronomers are unsure if or when it might have interacted with Andromeda in the past.

“One of the major motivations for this program was to probe potential interactions between M32 and Andromeda’s disk,” said Zhuo Chen, co-author, University of Washington.

Survey data from the Panchromatic Hubble Andromeda Southern Treasury allowed the team to study the history of star formation in Andromeda near M32. They found that this area showed signs of decreased star formation compared with other regions. The timing of this decrease, which this study finds began roughly 60 million years ago, could help constrain when the M32 galaxy interacted with Andromeda’s disk.

“We can’t explicitly say that we are seeing a decrease in star formation because of M32. But it’s right there, and it’s definitely the most likely suspect,” said Wainer.

The team plans to continue analyzing the Hubble data and combine it with data from ground-based observatories to gain additional insights into the history of Andromeda.

“There’s a strong scientific value to this archival data. Andromeda is important because it’s a neighbor that is close enough that we can see it in great detail while also getting a global perspective,” said Raja GuhaThakurta, co-author, University of California Santa Cruz.

An even greater global perspective is likely to come from NASA’s Nancy Grace Roman Space Telescope after it launches as early as Sunday, Aug. 30. Roman’s gigantic field of view can cover at least 100 times as much area as Hubble at near-infrared wavelengths in a single observation. A newly approved Roman observing program will image the entirety of Andromeda’s disk and areas of its surrounding halo, allowing astronomers to measure hundreds of millions of stars and enabling groundbreaking new science.

The Hubble Space Telescope has been operating for more than three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.

 

The subject of this NASA/ESA Hubble Space Telescope image is a spiral galaxy struggling against titanic forces that appear on galactic scales in space. This is NGC 4654, an intermediate spiral galaxy in the constellation Virgo (the Maiden). It is classified as an “intermediate” because its overall shape lies between spiral galaxies that have a bar across their centers and those that don’t. NGC 4654 has a weak bar structure at its center and is located 72 million light-years from Earth in the Virgo Cluster, a particularly massive and populous galaxy cluster.

NGC 4654 is particularly asymmetric, with a rounded and clearly-defined edge on one side and a long tail of gas stretching out from the opposite side — outside the field of view captured in this image. This gaseous tail is the result of ram pressure stripping, a force that galaxies can experience as they plow through space. NGC 4654 moves with such high velocity that it sweeps up and rams through the hot, rarefied gas filling the space between the Virgo Cluster’s galaxies. This intracluster medium in turn exerts a “ram pressure” on the galaxy, compressing the galaxy’s leading edge and dragging its gas behind the galaxy, creating the elongated tail.

It’s not just the galaxy’s gas that is unevenly distributed: its stars are too, and this is more unusual for a spiral galaxy. While the spiral arm on its leading edge is rich with stars and gas, the opposite arm noticeably lacks stars, influencing the galaxy’s lopsided spiral shape. Astronomers think that ram pressure alone is unlikely to cause this effect. Rather, NGC 4654 was also subjected to the gravitational force of fellow Virgo Cluster galaxy NGC 4639. While the two galaxies are far apart now, it’s thought that a fly-by interaction between them around 500 million years ago ripped away NGC 4654’s gas along one side, limiting star formation there and creating the asymmetry in its shape.

Many galaxies that undergo ram pressure stripping suffer reduced star formation rates as the cold gas that collapses to form their stars is pulled away and lost. NGC 4654, however, is still forming nearly two Suns’ worth of stars every year, a rate comparable to other galaxies of similar size. The active star formation is visible in the latest Hubble data included in this image. The data picks up on a wavelength of red light emitted by the clouds of energized gas where newborn stars lurk. The bright pink bubbles that appear across NGC 4654 — from its forward spiral arm, to around its weak bar, and out to the edge of its disk — are areas where these newborn stars shine.

The data used in this image came from two observing programs (#15654, #17502) that aim to link the gas in galaxies with star formation. By observing many prominent galaxies in the vicinity of our own, researchers hope to better understand how gas moves in galaxies, where and when it collapses to form stars and star clusters, and what effect those new stars have on the gas around them.

Text Credit: ESA/Hubble

Media Contact:

Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, MD
claire.andreoli@nasa.gov

Galaxies, stars, and living cells are all examples of local order emerging in the universe. At first glance, that seems to contradict one of physics’ oldest principles.

However, a recent study in Physical Review D offers a mathematical explanation for how these structures form while still obeying the second law of thermodynamics.

The second law of thermodynamics states that entropy, or disorder, in an isolated system always increases over time. Einstein famously said that “the second law of thermodynamics occupies a unique position among the laws of Nature,” reflecting how fundamental he believed the principle to be.

In its early days, the universe was smooth and uniform, with low entropy. As it expanded, gravity pulled gas into stars, stars into galaxies, and eventually made life possible. Each step seems to create order in one place, even though the universe as a whole became more disordered. Cosmologists have usually explained this by pointing to the universe’s growing volume.

Gravity as a Ledger, Not a Force

Mathematician Ginestra Bianconi at Queen Mary University of London addressed this problem with a framework called Gravity from Entropy. Rather than treating gravity as a fundamental force, the Gravity from Entropy framework proposes that it emerges from an information-based difference between two descriptions of spacetime geometry. One metric describes the actual shape of spacetime, while the other describes the geometry that matter and curvature would create. When these two match, gravity disappears. When they differ, gravity arises from the difference.

In the low-energy, weak-curvature limit, the framework reduces to general relativity. In the new study, Bianconi adds a thermodynamic perspective. She applies Gravity from Entropy to the standard model of an expanding universe and shows that the local geometric degrees of freedom follow the first law of thermodynamics, with their own temperature and pressure emerging from the equations.

Falling Density, Rising Total

One of the study’s central findings is the distinction between total entropy and entropy per unit volume. As the universe grows, the total entropy increases, just as the second law demands. However, the study found that entropy per unit volume decreases over time even as the universe’s total entropy continues to increase. Within the Gravity from Entropy framework, Bianconi proposes that this declining local entropy density may help explain how galaxies and other cosmic structures emerge.

The study also shows that these geometric temperatures change depending on what dominates the universe. In a universe dominated by matter or radiation, the temperature decreases over time. In a universe dominated by dark energy, like our own, they remain nearly constant. The framework even assigns a temperature and pressure to empty spacetime.

A Theory Still Waiting to Be Tested

“This work reveals how the Gravity from Entropy theory can tackle the challenging question of reconciling the second law of thermodynamics with the emergence of complexity in our universe,” stated Bianconi. “These results may open new avenues for investigating the long-standing problem of reconciling the foundations of cosmological irreversibility, the emergence of complex structures, and ultimately life with fundamental gravitational dynamics.”

So far, Gravity from Entropy has not been confirmed by observations. The theory makes predictions that future observations of large-scale cosmic structures and other gravitational phenomena could test. While it remains unproven, Bianconi believes it could offer a new way to link gravity, thermodynamics, quantum mechanics, and the rise of complexity in the universe.

Austin Burgess is a writer and researcher with a background in sales, marketing, and data analytics. He holds an MBA, a Bachelor of Science in Business Administration, and a data analytics certification. His work focuses on breaking scientific developments, with an emphasis on emerging biology, cognitive neuroscience, and archaeological discoveries.

Charles Ross spent 50 years building “Star Axis,” a naked-eye observatory in New Mexico. Now his masterwork is ready. How to share it with a changed world?

This image, which combines a background view from the Dark Energy Camera Legacy Survey with two inset images from the Very Large Telescope, shows an unusual pair of galaxies in the Fornax Cluster. The galaxies FCC 224 and FCC 240 are under scrutiny because they may have formed via a high-velocity collision between dwarf galaxies — the so-called “bullet-dwarf” model. Using new spectroscopy from the Very Large Telescope, Maria Luísa Buzzo (Yale University) and collaborators analyzed the ages and kinematics of the galaxies’ stars as well as the unusually bright globular clusters swirling around each galaxy. These data suggest that both galaxies are deficient in dark matter, and their stellar populations and globular clusters are all roughly 10 billion years old. The lack of dark matter and the uniform stellar ages are both consistent with the bullet-dwarf model, in which the collision strips away dark matter and ignites a burst of star formation. Since this type of collision can create more than two remnants, the team suggests searching along the trajectory defined by FCC 224 and FCC 240 for more fragments from the collision, some of which may contain the galaxies’ lost dark matter. To learn more about these galaxies and what they might mean for the bullet-dwarf mechanism, be sure to check out the full research article linked below.

Citation

“Dark-Matter-Deficient Twins: FCC 224 and FCC 240 as Possible Analogs of NGC 1052-DF2 and DF4,” Maria Luísa Buzzo et al 2026 ApJ 1005 15. doi:10.3847/1538-4357/ae7349

The post Featured Image: A Rare Pair of Galaxies Lacking Dark Matter appeared first on AAS Nova.

The iconic disks of spiral galaxies are well known across the local universe and now far beyond. A recent study looks at the Milky Way to determine when its own disk emerged.

Spinning into Spirals

The Milky Way, a grand spiral galaxy with stars and gas rotating in a disk, did not always look this way. Galaxies begin as chaotic clumps of gas and stars inside a knot of dark matter, and at some point in time, spiral galaxies must transform into the flat rotating disks we observe them as today. Recent JWST observations have uncovered disk galaxies emerging much earlier in the universe than previously thought, shifting our understanding of how quickly spiral galaxies come together and settle into disks. While we cannot study the detailed assembly history of these very distant galaxies, we can dissect galaxies in the local universe to build a better timeline of galaxy evolution.

Looking as close to home as possible, astronomers have used the kinematics and chemical makeup of stars in our own Milky Way to trace the moment when the galaxy started to host a rotating stellar disk. This period, known as the “spin-up,” marks when the bulk kinematic signature of the galaxy transitioned from one dominated by random motions to one dominated by a rotating disk.

Stars hold on to the kinematic and chemical information they are born with, so stars of different ages and metallicities across the galaxy should trace the development of the disk. Because stellar ages have been difficult to constrain observationally, studies of galactic spin-up have typically relied on readily available metallicity measurements as a proxy for age; however, metallicity is not a clear-cut age indicator, making it difficult to truly distinguish different stellar populations across the Milky Way’s disk. Luckily, new major surveys have recently provided stellar databases adding the stellar age measurements necessary to pin down when the Milky Way spun up.

Dawn of the Galactic Disk

Sofia Feltzing (Lund Observatory) and collaborators used a catalog of over 300,000 subgiant stars from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope with metallicities, kinematics, and crucial stellar ages to determine when the Milky Way began to host a stellar disk. After making quality cuts to ensure they included only the most robustly measured stars, the authors divided the sample into two distinct stellar populations that settled into the Milky Way’s disk differently: older stars with a high abundance of α elements (like oxygen, magnesium, and silicon) relative to iron and younger stars with low α-element abundances.

With these star samples, Feltzing and team analyzed how both stellar rotational velocity and age varied with metallicity to determine when the Milky Way spun up. They found that high-α stars clearly move from having random motions to being rotationally supported over a short range of metallicities about 12.5 billion years ago, while the low-α stars seem to begin in a rotating disk and stay there. When varying their selection criteria and looking at the full sample, the authors determined that the Milky Way spin-up happened between 12.1 to 12.5 billion years ago — the first time Milky Way spin-up has been age-dated in this way.

These results imply a rapid chemical evolution and change in kinematic properties as stars went from randomly orbiting to rotating in an ordered disk in the Milky Way. The authors suggest that future studies should focus on lower-metallicity stars to better disentangle stars in the disk from stars in the halo, which will lead to a more precise determination of the Milky Way’s spin-up. Upcoming large-scale surveys will make this possible and allow astronomers to build a better picture of galaxy formation in the early universe.

Citation

“Dawn of the Milky Way Disk: Determination of When a Rotationally Supported Disk Appears and Dating the Spin-up of the Disk,” Sofia Feltzing et al 2026 ApJL 1004 L28. doi:10.3847/2041-8213/ae6f14

The post Dating the Dawn of the Milky Way Disk appeared first on AAS Nova.

The sharp-eyed and far-seeing Euclid space telescope has picked up 31 early quasars that have evaded detection until now.

The post Euclid Telescope Finds Quasars Within 700 Million Years of the Big Bang appeared first on Sky & Telescope.

The only three measurables in galactic astronomy are the position, luminosity and spectrum of the source light received in our telescopes. There is no distance information without unprovable assumptions, hence no direct measurement of size or age of the universe. Thus we may conclude it is young in agreement with the Bible.

New research reveals how an unusual celestial object resembling a cosmic “bullseye” could offer clues to one of the most perplexing phenomena in our universe.

The research, undertaken by physicists Pierre Sikivie and Yuxin Zhao at the University of Florida, focuses on an astronomical feature quite unlike any other—the galaxy LEDA 1313424, whose concentric rings have garnered it the apt nickname of the “Bullseye galaxy.”

Based on Sikivie and Zhao’s recent research, detailed in a new paper that appeared in The Astrophysical Journal, quantum behavior related to long-mysterious dark matter may hold the key to the galaxy’s unusual appearance.

Unraveling a Bullseye Galaxy’s Circular Secrets

In the past, astronomers have attempted to explain LEDA 1313424’s unusual concentric appearance as the likely result of an ancient collision between two galaxies.

Not so, according to Sikivie and Zhao, who now take a vastly different approach by arguing that a better explanation may involve a Bose-Einstein condensate of axions, a variety of extremely light hypothetical particles.

This concept has much deeper roots that go back close to a century ago, when the first galaxy featuring an unusual concentric ring was discovered. This example, dubbed the Cartwheel galaxy, was only the first in a succession of similar astronomical discoveries involving galaxies with “ringed” appearances that incorporate as many as three annular features.

Unraveling an Annular Enigma

Explaining why these galaxies look this way has remained elusive. One theory proposed by astronomers, as noted earlier, involves impacts between two galaxies, which could create waves of density whose ripples become evident in ring-like structures surrounding the resulting galaxies.

However, a discovery in 2025 by Imad Pasha, a Yale University astronomer, and his colleagues presented an even stranger development in this ongoing concentric saga: the discovery of a galaxy that possesses not three rings, but nine of them. With its discovery, this remarkable celestial object’s unusual appearance garnered the nickname now familiar to us: “The Bullseye galaxy.”

One theory that astronomers believed may account for the galaxy’s nine concentric structures had been a hypothetical impact—and a very energetic one—that occurred about 56 million years ago. However, while investigating this possibility, Sikivie and Zhao say a problem emerged: this would mean that the outermost ring in the galaxy would have had to travel at a speed of 758 miles per second as it blasted outward from the galaxy’s center.

This speed, they say, is impossible to reconcile with what astronomers can already discern about the nature of the supposed collusion, as well as the well-characterized behavior of galactic material observed in other regions of the cosmos.

An Alternative Approach

In an effort to get to the bottom of the mystery behind this unique galaxy, Sikivie and Zhao have put forward an alternative idea: that the rings in the Bullseye galaxy might instead be a byproduct of dark matter’s mysterious properties.

According to astronomers, dark matter is believed to be a nonluminous material that populates our universe, contributing around 85% of its total mass. Despite its ubiquity, direct detections that could confirm its existence have remained elusive.

However, there are some intriguing cosmic phenomena that astronomers are aware of that are very good candidates for being indirect evidence of this mysterious material. These observations include gravitational motion that occurs in galaxies, whereby the accumulation of dark matter is believed to manifest in the appearance of spherical halos encircling them.

In the past, Sikivie has explored this possibility, and whether current prevailing theories about dark matter, such as the idea that hypothetical particles known as axions, may offer the best interpretation of the physical reality behind dark matter.

If dark matter is indeed related to axions, it would also be required to obey what astrophysicists call conservation of angular momentum. According to Sikivie, when axions and galaxies interact, a phenomenon should emerge where portions of dark matter halos closest to the center would become oriented in structural forms known as “caustic rings.”

“We had earlier proposed that disk galaxies have caustic rings of dark matter with a pattern of ring radii, very similar to the pattern of ring radii observed in LEDA 1313424,” Sikivie recently said.

With this idea in mind, Sikivie and Lhao then turned their attention to the mysterious bullseye of LEDA 1313424 and “fitted the observed ring radii to the pattern of ring radii in the caustic ring interpretation,” from which they discerned that “LEDA’s rings are the imprint of caustic rings of dark matter on the baryonic matter in LEDA’s disk.”

Strange Quantum Behaviors

A further aspect of the researchers’ theory involves the quantum behavior that axions are expected to engage in.

Under extremely cold conditions, these hypothetical dark matter particles could collectively occupy the same quantum state, forming what is known as a Bose-Einstein condensate—a strange state of matter in which quantum effects become visible on macroscopic scales.

According to the team, such a condensate could interact with ordinary matter in ways that match astronomical observations. If the duo is correct, this could imply that ring-shaped galaxies such as LEDA may not result from galactic collisions at all—instead, these unique cosmic structures might be evidence of dark matter axions that have undergone Bose-Einstein condensation.

Presently, much like dark matter, axions have remained hypothetical and frustratingly difficult to detect. Of course, given their elusiveness, this also makes them a very good candidate in terms of helping scientists close in on the dark matter mystery, and new models are helping to provide potentially compelling new resolutions for such problems.

For now, mysterious ringed galaxies remain mysterious. However, as the work of researchers like Sikivie and Lhao progresses, one of astronomy’s more unusual recent discoveries is gradually coming into focus, while providing fresh insight into the intriguing quantum nature of dark matter.

The team’s recent paper, “The Nine Rings of the Galaxy LEDA 1313424,” appeared in The Astrophysical Journal.

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.

A star-forming galaxy in the early universe might have sent a ghostly particle known as a neutrino crashing into the ice at Earth’s South Pole, after an 11 billion-year journey through space.

The post “Shadow Blaster” Galaxy Might Have Sent High-Energy Neutrino to Earth appeared first on Sky & Telescope.

This NASA Hubble Space Telescope image features a galaxy cluster, called CL0016+1609 or MACS J0018.5+1626, that is very bright at X-ray wavelengths and is one of the most extensively studied clusters at X-ray and radio wavelengths. The X-ray observations of this cluster revealed that it is two clusters merging along our line of sight.

Researchers requested time to observe CL0016+1609 with Hubble’s Advanced Camera for Surveys because that data would help them accurately measure the cluster’s dark-matter distribution, which helps them study the merger and the role of CL0016+1609 in the large-scale structure of the universe. Hubble can’t directly see dark matter, but its infrared and visible light observations can detect dark matter’s gravitational lensing effects on the normal matter Hubble observes.

The data in this image also includes observations with Hubble’s Wide Field Camera 3 taken as part of an observing program that obtained the first Hubble infrared images of 46 massive galaxy clusters and looked for distant galaxies gravitationally lensed by these clusters. Called RELICS (Reionization Lensing Cluster Survey), this survey found some 300 high-redshift candidate galaxies lensed by these clusters.

You can see the faint vertical arc of one of these distant galaxies in the image above. Look for it just to the left of the large elliptical galaxies in the center of the image. Another brighter, though shorter arc is visible just above and to the right of the large elliptical galaxies in the center of the image.

Media Contact:

Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, MD
claire.andreoli@nasa.gov

This NASA Hubble Space Telescope image features a galaxy cluster, called CL0016+1609 or MACS J0018.5+1626, that is very bright at X-ray wavelengths and is one of the most extensively studied clusters at X-ray and radio wavelengths. The X-ray observations of this cluster revealed that it is two clusters merging along our line of sight.

Researchers requested time to observe CL0016+1609 with Hubble’s Advanced Camera for Surveys because that data would help them accurately measure the cluster’s dark-matter distribution, which helps them study the merger and the role of CL0016+1609 in the large-scale structure of the universe. Hubble can’t directly see dark matter, but its infrared and visible light observations can detect dark matter’s gravitational lensing effects on the normal matter Hubble observes.

The data in this image also includes observations with Hubble’s Wide Field Camera 3 taken as part of an observing program that obtained the first Hubble infrared images of 46 massive galaxy clusters and looked for distant galaxies gravitationally lensed by these clusters. Called RELICS (Reionization Lensing Cluster Survey), this survey found some 300 high-redshift candidate galaxies lensed by these clusters.

You can see the faint vertical arc of one of these distant galaxies in the image above. Look for it just to the left of the large elliptical galaxies in the center of the image. Another brighter, though shorter arc is visible just above and to the right of the large elliptical galaxies in the center of the image.

Media Contact:

Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, MD
claire.andreoli@nasa.gov

The post Hubble Glimpses Merging Galaxy Clusters appeared first on NASA Science.

Une anomalie au cœur de la Voie lactée intrigue les astronomes depuis des décennies. Et les dernières observations du télescope spatial James-Webb viennent de transformer une curiosité en véritable casse-tête cosmique. De quoi changer notre vision de la formation des galaxies.

Astronomers have made a major breakthrough by directly detecting the gas that fueled star formation in some of the universe’s earliest galaxies. The discovery offers a new way to understand how the first galaxies formed and evolved shortly after the Big Bang. The universe began with the Big Bang about 13.8 billion years ago. Over […]

The post Astronomers detect the fuel for star formation in some of the universe’s earliest galaxies appeared first on Knowridge Science Report.

A deep spectrum of a mysterious "little red dot" reveals a supermassive black hole cocooned in gas so dense it's opaque — but glowing in the infrared.

The post "Little Red Dot" Is a Cocooned Black Hole appeared first on Sky & Telescope.